Camshaft phaser

ABSTRACT

An internal combustion engine includes a crankshaft rotatable about a crankshaft axis and a camshaft rotatable by the crankshaft about a camshaft axis. The internal combustion engine also includes an oil supply, an engine cover, and a drive member disposed within the engine cover for transferring rotational motion from the crankshaft to the camshaft. A camshaft phaser is disposed within the engine cover for controllably varying the phase relationship between the crankshaft and the camshaft by using oil from the oil supply. A sealing arrangement defines a dry zone to isolate the drive member from oil used to rotate the output member relative to the input member.

TECHNICAL FIELD OF INVENTION

The present invention relates to an internal combustion engine with a camshaft phaser which uses pressurized oil to vary the phase relationship between a crankshaft and a camshaft of the internal combustion engine; more particularly to such an internal combustion engine which includes a drive belt for transmitting rotational motion from the crankshaft to the camshaft; and still even more particularly to such an internal combustion engine which includes a sealing arrangement to seal the drive belt from the oil used to vary the phase relationship between the crankshaft and the camshaft.

BACKGROUND OF INVENTION

A typical vane-type camshaft phaser for changing the phase relationship between a crankshaft and a camshaft of an internal combustion engine generally comprises a plurality of outwardly-extending vanes on a rotor interspersed with a plurality of inwardly-extending lobes on a stator, forming alternating advance and retard chambers between the vanes and lobes. Engine oil is selectively supplied to either the advance chambers or the retard chambers and vented from the other of the advance and retard chambers in order to rotate the rotor within the stator and thereby change the phase relationship between the camshaft and the crankshaft. Some camshaft phasers include a valve spool within the camshaft phaser in order to selectively supply and vent oil to and from the advance and retard chambers as necessary in order to achieve the desired phase relationship between the camshaft and the crankshaft. When the oil is vented from either the advance chambers or the retard chambers, the oil is typically drained out of the camshaft phaser and allowed to reach a drive member, such as a chain, gear, or belt, which transfers rotational motion from the crankshaft to the camshaft phaser. While this may be acceptable to some drive members, particularly chains and gears, other drive members, particularly belts, may not tolerate exposure to oil.

U.S. Pat. No. 5,361,735 to Butterfield et al. teaches a camshaft phaser having a flexible diaphragm at one axial end thereof to prevent oil from the camshaft phaser from reaching the drive belt. The flexible diaphragm is positioned between a valve spool and an actuator which alters the position of the valve spool. Consequently, the actuator pushes on the valve spool through the flexible diaphragm during operation. Since the flexible diaphragm is rotating at the rotational speed of the camshaft during operation and the rotational actuator is rotationally stationary, durability issues with the flexible diaphragm may result, particularly if there is misalignment in concentricity between the actuator and the center of the flexible diaphragm.

What is needed is a camshaft phaser which minimizes or eliminates one or more the shortcomings as set forth above.

SUMMARY OF THE INVENTION

Briefly described, an internal combustion engine includes a crankshaft rotatable about a crankshaft axis and a camshaft rotatable by the crankshaft about a camshaft axis. The internal combustion engine also includes an oil supply, an engine cover, and a drive member disposed within the engine cover for transferring rotational motion from the crankshaft to the camshaft. A camshaft phaser is disposed within the engine cover for controllably varying the phase relationship between the crankshaft and the camshaft. The camshaft phaser includes an input member driven by the drive member, an output member rotatable with the camshaft wherein the output member is rotatable relative to the input member by oil from the oil supply thereby varying the phase relationship between the crankshaft and the camshaft, and a valve spool within the camshaft phaser and moveable therein between 1) an advance position to direct oil from the oil supply to cause the input member to rotate relative to the output member to advance the camshaft relative to the crankshaft and 2) a retard position to direct oil from the oil supply to cause the input member to rotate relative to the output member to retard the camshaft relative to the crankshaft. An actuator moves the valve spool between the advance position and the retard position and a sealing arrangement defines a dry zone with one of the engine cover and the actuator to isolate the drive member from oil used to rotate the output member relative to the input member.

Further features and advantages of the invention will appear more clearly on a reading of the following detailed description of the preferred embodiment of the invention, which is given by way of non-limiting example only and with reference to the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

This invention will be further described with reference to the accompanying drawings in which:

FIG. 1 is an exploded isometric view of an internal combustion engine in accordance with the present invention;

FIG. 2 is an axial cross-sectional view of the internal combustion engine in accordance with the present invention;

FIG. 3 is a radial cross-sectional view of a camshaft phaser of the internal combustion engine in accordance with the present invention;

FIG. 4A is an axial cross-sectional view of the camshaft phaser, taken through section line 4-4 of FIG. 3, showing an actuator in an energized state of operation;

FIG. 4B is an axial cross-sectional view of the camshaft phaser, taken through section line 4-4 of FIG. 3, showing the actuator in an unenergized state of operation;

FIG. 5 is an enlargement of a portion of FIG. 2;

FIG. 6 is an axial cross-sectional view of an alternative internal combustion engine in accordance with the present invention; and

FIG. 7 is an axial cross-sectional view of another alternative internal combustion engine in accordance with the present invention.

DETAILED DESCRIPTION OF INVENTION

Referring to FIGS. 1 and 2, an internal combustion engine 10 is shown in accordance with the present invention. Internal combustion engine 10 generally includes one or more pistons (not shown), a crankshaft 12 which rotates about a crankshaft axis 14, a camshaft 16 which is supported in a camshaft support 18 and rotates about a camshaft axis 20, and a camshaft phaser 22 which rotates about camshaft axis 20. Internal combustion engine 10 may be, for example only, spark ignited or compression ignited and may be fueled by any liquid fuel or gaseous fuel customarily used, for example only, liquid fuels such as gasoline, diesel fuel, alcohol, ethanol, and the like and blends thereof or gaseous fuels such as natural gas, propane, and the like. The pistons, which are connected to crankshaft 12, reciprocate as a result of combustion of the fuel within the respective combustion chambers (not shown). Reciprocation of the pistons causes crankshaft 12 to rotate about crankshaft axis 14. Crankshaft 12 includes a crankshaft pulley 24 which may be toothed as shown and which rotates a drive member 26, for example, drive belt which is toothed to mate with crankshaft pulley 24. Camshaft phaser 22 is rotated by drive member 26 and is connected to camshaft 16, consequently, camshaft 16 rotates about camshaft axis 20 as a result of crankshaft 12. Rotation of camshaft 16 about camshaft axis 20 causes one or more combustion valves (not shown) to open and close. The combustion valves allow a charge of air and/or fuel into the combustion chambers and/or exhaust constituents out of the combustion chambers. Camshaft phaser 22 allows the phase of rotation of camshaft 16 relative to crankshaft 12 to be varied, thereby varying the timing of opening and/or closing of the combustion valves relative to crankshaft 12 as will be described in greater detail later. An engine cover 28 encloses crankshaft pulley 24, drive member 26, and camshaft phaser 22.

With continued reference to FIGS. 1 and 2 and now with additional reference to FIG. 3, camshaft phaser 22 uses pressurized oil to change the phase relationship of camshaft 16 relative to crankshaft 12. As shown, camshaft phaser 22 is what is commonly referred to in the art as a vane-type camshaft phaser. Camshaft phaser 22 generally includes a stator 30 which acts as an input member, a rotor 32 which acts as an output member and which is disposed coaxially within stator 30, a back cover 34 closing off one end of stator 30, a front cover 36 closing off the other end of stator 30, a camshaft phaser attachment bolt 40 for attaching camshaft phaser 22 to camshaft 16, and a valve spool 42 for controlling oil as will be described later which is supplied by an oil supply 44 of internal combustion engine 10. An actuator 46 is provided for positioning valve spool 42 to achieve a desired rotational position of rotor 32 relative to stator 30 as will also be described later. The various elements of camshaft phaser 22 will be described in greater detail in the paragraphs that follow.

Stator 30 is generally cylindrical and includes a plurality of radial chambers 48 (only one radial chamber 48 is labeled in FIG. 1) defined by a plurality of lobes 50 extending radially inward. In the embodiment shown, there are four lobes 50 defining four radial chambers 48, however, it is to be understood that a different number of lobes 50 may be provided to define radial chambers 48 equal in quantity to the number of lobes 50. Stator 30 may also include a camshaft phaser pulley 52 which is toothed as shown and formed integrally therewith or otherwise fixed thereto. Camshaft phaser pulley 52 is configured to be driven by drive member 26. While the drive arrangement between crankshaft 12 and camshaft phaser 22 has been illustrated as using pulleys and a belt, it should now be understood that other drive arrangements may be used, for example only, sprockets and a chain or gears.

Rotor 32 includes a central hub 54 with a plurality of vanes 56 extending radially outward therefrom and a central through bore 58 extending axially therethrough. The number of vanes 56 is equal to the number of radial chambers 48 provided in stator 30. Rotor 32 is coaxially disposed within stator 30 such that each vane 56 divides each radial chamber 48 into advance chambers 60 and retard chambers 62. The radial tips of lobes 50 are mateable with central hub 54 in order to separate radial chambers 48 from each other. Each of the radial tips of lobes 50 and the tips of vanes 56 may include one of a plurality of wiper seals 64 to substantially seal adjacent advance chambers 60 and retard chambers 62 from each other.

Back cover 34 is sealingly secured, using cover bolts 66, to the axial end of stator 30 that is proximal to camshaft 16. A back cover seal 68, for example only, an o-ring, may be provided between back cover 34 and stator 30 in order to provide an oil-tight seal between the interface of back cover 34 and stator 30. Tightening of cover bolts 66 prevents relative rotation between back cover 34 and stator 30. Back cover 34 includes a back cover central bore 70 extending coaxially therethrough. The end of camshaft 16 is received coaxially within back cover central bore 70 such that camshaft 16 is allowed to rotate relative to back cover 34. In an alternative arrangement, camshaft phaser pulley 52 may be integrally formed or otherwise attached to back cover 34 rather than to stator 30 as described previously.

Similarly, front cover 36 is sealingly secured, using cover bolts 66, to the axial end of stator 30 that is opposite back cover 34. A front cover seal 72, for example only, an o-ring, may be provided between front cover 36 and stator 30 in order to provide an oil-tight seal between the interface of front cover 36 and stator 30. Cover bolts 66 pass through back cover 34 and stator 30 and threadably engage front cover 36, thereby clamping stator 30 between back cover 34 and front cover 36 to prevent relative rotation between stator 30, back cover 34, and front cover 36. In this way, advance chambers 60 and retard chambers 62 are defined axially between back cover 34 and front cover 36.

Camshaft phaser 22 is attached to camshaft 16 with camshaft phaser attachment bolt 40 which extends coaxially through central through bore 58 of rotor 32 and threadably engages camshaft 16, thereby clamping rotor 32 securely to camshaft 16. In this way, relative rotation between stator 30 and rotor 32 results in a change in phase relationship or timing between crankshaft 12 and camshaft 16.

With continued reference to FIGS. 1-3 and now with additional reference to FIGS. 4A, 4B, and 5, pressurized oil is selectively supplied to advance chambers 60 and vented from retard chambers 62 in order to cause relative rotation between stator 30 and rotor 32 which results in advancing the timing of camshaft 16 relative to crankshaft 12. Conversely, oil is selectively supplied to retard chambers 62 and vented from advance chambers 60 in order to cause relative rotation between stator 30 and rotor 32 which results in retarding the timing of camshaft 16 relative to crankshaft 12. Advance oil passages 74 may be provided in rotor 32 for supplying and venting oil to and from advance chambers 60 while retard oil passages 76 may be provided in rotor 32 for supplying and venting oil to and from retard chambers 62. Supplying and venting of oil to and from advance chambers 60 and retard chambers 62 is controlled by valve spool 42, as will be discussed in the paragraphs that follow, which is coaxially disposed slidably within a valve bore 78 of camshaft phaser attachment bolt 40 such that valve bore 78 is centered about camshaft axis 20.

Oil supply 44 provides a supply of pressurized oil to valve spool 42 through radial camshaft passages 80 which communicate with a camshaft counterbore 82 which forms a camshaft annular oil passage 84 with a portion of camshaft phaser attachment bolt 40. The oil then passes from camshaft annular oil passage 84 to an axial rotor oil passage 86 which extends axially into rotor 32. The oil is subsequently communicated to an annular rotor oil supply groove 88 which extends radially outward from central through bore 58 and intersects axial rotor oil supply passage 86. Annular rotor oil supply groove 88 is axially aligned with bolt oil supply passages 90 which extend radially through camshaft phaser attachment bolt 40 from valve bore 78. In this way, oil from oil supply 44 is supplied to valve spool 42.

Valve spool 42 includes a body 92 that is generally cylindrical, hollow, and dimensioned to provide annular clearance between body 92 and valve bore 78 of camshaft phaser attachment bolt 40. Valve spool 42 also includes an advance land 94 extending radially outward from body 92 for selectively blocking fluid communication between bolt oil supply passages 90 and advance bolt passages 96 which extend radially outward through camshaft phaser attachment bolt 40 from valve bore 78 and communicate with advance oil passages 74 of rotor 32 through an annular rotor advance oil groove 98 which extends radially outward from central through bore 58. Advance land 94 fits within valve bore 78 of camshaft phaser attachment bolt 40 in a close fitting relationship to substantially prevent oil from passing between advance land 94 and valve bore 78. Valve spool 42 also includes a retard land 100 extending radially outward from body 92 for selectively blocking fluid communication between bolt oil supply passages 90 and retard bolt passages 102 which extend radially outward through camshaft phaser attachment bolt 40 from valve bore 78 and communicate with retard oil passages 76 of rotor 32 through an annular rotor retard oil groove 104 which extends radially outward from central through bore 58. Retard land 100 is spaced axially from advance land 94 and fits within valve bore 78 of camshaft phaser attachment bolt 40 in a close fitting relationship to substantially prevent oil from passing between retard land 100 and valve bore 78.

Valve spool 42 is axially moveable within valve bore 78 with input from actuator 46 and a spool spring 106 which is positioned axially between valve spool 42 and the bottom of valve bore 78. When actuator 46 is in an unenergrized state of operation as shown in FIG. 4B, valve spool 42 is positioned in a retard position, by force of spool spring 106, to allow pressurized oil to be supplied to retard chambers 62 as shown by arrows P. At the same time, oil within advance chambers 60 is allowed to be vented through a central passage 108 formed coaxially through valve spool 42 and then out through the end of valve bore 78 as shown by arrows V.

Conversely, when actuator 46 is in an energized state of operation as shown in FIG. 4A, valve spool 42 is positioned in an advance position, by force from actuator 46 overcoming force of spool spring 106, to allow pressurized oil to be supplied to advance chambers 60 as shown by arrows P. At the same time, oil within retard chambers 62 is allowed to be vented through the end of valve bore 78 as shown by arrows V.

Drive member 26 may not be compatible with the oil supplied to camshaft phaser 22, consequently, a dry zone 110 may be formed within engine cover 28. Drive member 26 is located within dry zone 110 which is substantially free of the oil supplied to camshaft phaser 22. Dry zone 110 is formed by a sealing arrangement which may comprise an engine cover to camshaft phaser seal 112 and an engine to camshaft phaser seal 114. The sealing arrangement will be described in greater detail in the paragraphs that follow.

Referring now to FIGS. 1, 2, and 5, engine cover to camshaft phaser seal 112 provides a seal between engine cover 28 and front cover 36. Engine cover 28 includes an engine cover seal support 116 which is ring-shaped and substantially centered about camshaft axis 20. Engine cover seal support 116 extends axially away from engine cover 28 toward camshaft phaser 22 into dry zone 110. Engine cover to camshaft phaser seal 112 includes an engine cover to camshaft phaser seal supporting body 118 which is ring shaped and secured coaxially within engine cover seal support 116, for example, by a press fit. Alternatively, engine cover to camshaft phaser seal supporting body 118 may be secured to engine cover seal support 116 by surrounding engine cover seal support 116, i.e. the radial relationship between engine cover to camshaft phaser seal supporting body 118 and engine cover seal support 116 may be reversed from the relationship shown in the figures. Engine cover to camshaft phaser seal supporting body 118 may be made of a rigid material, for example, metal or plastic. Engine cover to camshaft phaser seal 112 also includes an engine cover to camshaft phaser seal lip seal 120 which extends radially inward from engine cover to camshaft phaser seal supporting body 118. Engine cover to camshaft phaser seal lip seal 120 may be molded and bonded to engine cover to camshaft phaser seal supporting body 118 and may be made of an elastomeric or rubber-like material, for example only, Nitrile Butadiene Rubber (NBR), Viton®, or silicone. Front cover 36 includes a front cover sealing body 122 for radially mating with engine cover to camshaft phaser seal lip seal 120. Front cover sealing body 122 may include a sleeve (not show) in a radially surrounding relationship which provides the necessary harness and surface finish to withstand rubbing with respect to engine cover to camshaft phaser seal lip seal 120, however, the sleeve may be omitted as shown if front cover sealing body 122 is made from a material of adequate hardness and surface finish. Front cover sealing body 122 is ring-shaped and extends axially away from front cover 36 toward engine cover 28 in a coaxial relationship with engine cover seal support 116. Front cover sealing body 122 is sized to elastically deform engine cover to camshaft phaser seal lip seal 120 when assembled in order to provide an oil-tight seal between front cover sealing body 122 and engine cover to camshaft phaser seal lip seal 120. Engine cover to camshaft phaser seal lip seal 120 is sized to provide sufficient compliance to accommodate mismatch in concentricity between engine cover to camshaft phaser seal 112 and front cover sealing body 122 due to manufacturing tolerances. In this way, oil that is vented from advance chambers 60 and retard chambers 62 through the end of valve bore 78 is prevented from entering dry zone 110 as camshaft phaser 22 rotates with respect to engine cover to camshaft phaser seal 112 in operation. In addition to engine cover to camshaft phaser seal lip seal 120, engine cover to camshaft phaser seal 112 may include a dust seal lip which protects engine cover to camshaft phaser seal lip seal 120 from external contamination that may have undesirable effects on engine cover to camshaft phaser seal lip seal 120.

Engine to camshaft phaser seal 114 provides a seal between camshaft support 18 and back cover 34. A camshaft support bore 124, which is cylindrical, extends into camshaft support 18 in a coaxial relationship with camshaft 16. Engine to camshaft phaser seal 114 includes an engine to camshaft phaser seal supporting body 126 which is ring shaped and secured coaxially within camshaft support bore 124, for example, by a press fit. Engine to camshaft phaser seal supporting body 126 may be made of a rigid material, for example, metal or plastic. Engine to camshaft phaser seal 114 also includes an engine to camshaft phaser seal lip seal 128 which extends radially inward from engine to camshaft phaser seal supporting body 126. Engine to camshaft phaser seal lip seal 128 may be molded and bonded to engine to camshaft phaser seal supporting body 126 and may be made of an elastomeric or rubber-like material, for example only, Nitrile Butadiene Rubber (NBR), Viton®, or silicone. Engine to camshaft phaser seal 114 may also include an engine to camshaft phaser seal dust lip seal 130 which extends radially inward from engine to camshaft phaser seal supporting body 126 and may be made from the same material as engine to camshaft phaser seal lip seal 128. Engine to camshaft phaser seal dust lip seal 130 protects engine to camshaft phaser seal lip seal 128 from external contamination that may have undesirable effects on engine to camshaft phaser seal lip seal 128. Back cover 34 includes a back cover sealing body 132 for radially mating with engine to camshaft phaser seal lip seal 128. Back cover sealing body 132 is ring-shaped and extends axially away from back cover 34 into camshaft support bore 124 in a coaxial relationship with camshaft support bore 124. Back cover sealing body 132 is sized to elastically deform engine to camshaft phaser seal lip seal 128 when assembled in order to provide an oil-tight seal between back cover sealing body 132 and engine to camshaft phaser seal lip seal 128.

Engine cover 28 includes an engine cover bore 134 extending therethrough in a substantially coaxial relationship with camshaft 16. Actuator 46 is received coaxially within engine cover bore 134 and is fixed to engine cover 28 to prevent relative rotation between engine cover 28 and actuator 46. An engine cover to actuator seal 136, which may be an O-ring as shown, is disposed between actuator 46 and engine cover 28. In this way, oil that is vented from advance chambers 60 and retard chambers 62 through the end of valve bore 78 is prevented from exiting engine cover 28 between the interface of engine cover 28 and actuator 46. It should be noted that engine cover to actuator seal 136 is a static seal, unlike engine cover to camshaft phaser seal 112 and engine to camshaft phaser seal 114 which are dynamic seals, since there is no relative movement between engine cover 28 and actuator 46.

With continued reference to FIGS. 1, 2, and 5 and now with additional reference to FIG. 7, a rotor drain passage 138 is provided axially through central hub 54 of rotor 32 in order to return oil to oil supply 44 that is vented from advance chambers 60 and retard chambers 62 through the end of valve bore 78. In order for rotor drain passage 138 to receive oil that has been vented from advance chambers 60 and retard chambers 62, a washer 140 that is captured axially between camshaft phaser attachment bolt 40 and rotor 32 may include a notch 142 therethrough to allow the vented oil to enter rotor drain passage 138. The oil exits the rotor drain passage 138 that is proximal to camshaft 16 and is prevented from entering dry zone 110 by engine to camshaft phaser seal 114 and is subsequently returned to oil supply 44. It should be noted that rotor drain passage 138 and notch 142 are also present in the other figures, however, are not visible because of the particular sections that are shown.

Alternatively, as shown in FIG. 6, engine cover to camshaft phaser seal 112 may be fixed to actuator 46′ rather than to engine cover 28′. Actuator 46′ includes an actuator seal bore 144 which is substantially coaxial with camshaft 16. Engine cover to camshaft phaser seal 112 may be secured coaxially within actuator seal bore 144, for example, by press fit. Also alternatively, as shown in FIG. 7, actuator 46″ may be provided which is integrally housed as part of engine cover 28″. Engine cover to camshaft phaser seal 112 may be supported by engine cover seal support 116″ which is configured similar to engine cover seal support 116 as described previously.

While not shown, it should now be understood that camshaft phaser 22 may include a bias spring that either partially or completely offsets the natural retarding torque induced by the overall valve train friction, balances performance times, or helps return the phaser to a default position of rotor 32 within stator 30. The bias spring may be grounded at one end thereof to front cover 36 and may be attached at the other end thereof to rotor 32 for biasing rotor 32 relative to stator 30.

While this invention has been described in terms of preferred embodiments thereof, it is not intended to be so limited, but rather only to the extent set forth in the claims that follow. 

We claim:
 1. An internal combustion engine having a crankshaft rotatable about a crankshaft axis and a camshaft rotatable by said crankshaft about a camshaft axis, said internal combustion engine comprising: a) an oil supply; b) an engine cover; c) a drive member disposed within said engine cover for transferring rotational motion from said crankshaft to said camshaft; d) a camshaft phaser disposed within said engine cover for controllably varying the phase relationship between said crankshaft and said camshaft, said camshaft phaser comprising: i) an input member driven by said drive member; ii) an output member rotatable with said camshaft wherein said output member is rotatable relative to said input member by oil from said oil supply, thereby varying the phase relationship between said crankshaft and said camshaft; and iii) a valve spool within said camshaft phaser and moveable therein between 1) an advance position to direct oil from said oil supply to cause said input member to rotate relative to said output member to advance said camshaft relative to said crankshaft and 2) a retard position to direct oil from said oil supply to cause said input member to rotate relative to said output member to retard said camshaft relative to said crankshaft; e) an actuator for moving said valve spool between said advance position and said retard position; and f) a sealing arrangement defining a dry zone with one of said engine cover and said actuator to isolate said drive member from oil used to rotate said output member relative to said input member.
 2. An internal combustion engine as in claim 1 wherein: said input member is a stator having a plurality of lobes; said output member is a rotor disposed within said stator, said rotor having a plurality of vanes interspersed with said lobes such that said rotor is rotatable within said stator about said camshaft axis and defining alternating advance chambers and retard chambers, wherein said advance chambers receive oil in order to change the phase relationship between said crankshaft and said camshaft in an advance direction and said retard chambers receive oil in order to change the phase relationship between said camshaft and said crankshaft in a retard direction; said camshaft phaser further comprising a front cover closing off one end of said stator; and said sealing arrangement comprising an engine cover to camshaft phaser seal to seal between said engine cover and said front cover or between said actuator and said front cover.
 3. An internal combustion engine as in claim 2 wherein said engine cover to camshaft phaser seal is a radial seal.
 4. An internal combustion engine as in claim 2 wherein said camshaft phaser rotates relative to said engine cover to camshaft phaser seal.
 5. An internal combustion engine as in claim 2 wherein said engine cover includes a ring-shaped engine cover seal support extending axially from said engine cover toward said camshaft phaser and said engine cover to camshaft phaser seal is fixed to said engine cover seal support.
 6. An internal combustion engine as in claim 5 wherein said front cover includes a ring-shaped front cover sealing body extending axially from said front cover toward said engine cover such that said engine cover to camshaft phaser seal seals against said front cover sealing body.
 7. An internal combustion engine as in claim 2 wherein: said camshaft phaser further comprises a back cover closing off the other end of said stator, said back cover including a back cover central bore extending axially therethrough; said internal combustion engine further comprising a camshaft support which supports said camshaft; and said sealing arrangement further comprising an engine to camshaft phaser seal to seal between said camshaft phaser and said camshaft support.
 8. An internal combustion engine as in claim 7 wherein said engine to camshaft phaser seal is a radial seal.
 9. An internal combustion engine as in claim 7 wherein said camshaft phaser rotates relative to said engine to camshaft phaser seal.
 10. An internal combustion engine as in claim 7 wherein said camshaft support defines a camshaft support bore and said engine to camshaft phaser seal is located within said camshaft support bore.
 11. An internal combustion engine as in claim 10 wherein said back cover includes a ring-shaped back cover sealing body extending axially from said back cover into said camshaft support bore such that said engine to camshaft phaser seal seals against said back cover sealing body.
 12. An internal combustion engine as in claim 2 wherein said engine cover to camshaft phaser seal is fixed to said actuator.
 13. An internal combustion engine as in claim 12 wherein said actuator includes an actuator seal bore extending axially into said actuator and said engine cover to camshaft phaser seal is fixed within said actuator seal bore.
 14. An internal combustion engine having a crankshaft rotatable about a crankshaft axis and a camshaft rotatable by said crankshaft about a camshaft axis, said internal combustion engine comprising: a) an oil supply; b) an engine cover; c) a drive member disposed within said engine cover for transferring rotational motion from said crankshaft to said camshaft; d) a camshaft phaser disposed within said engine cover for controllably varying the phase relationship between said crankshaft and said camshaft, said camshaft phaser comprising: i) an input member driven by said drive member; ii) an output member rotatable with said camshaft wherein said output member is rotatable relative to said input member by oil from said oil supply, thereby varying the phase relationship between said crankshaft and said camshaft; and iii) a valve spool within said camshaft phaser and moveable therein for directing oil from said oil supply; e) an actuator for moving said valve spool; and f) a sealing arrangement defining a dry zone with one of said engine cover and said actuator to isolate said drive member from oil directed by said valve spool.
 15. An internal combustion engine as in claim 14 wherein: said input member is a stator having a plurality of lobes; said output member is a rotor disposed within said stator, said rotor having a plurality of vanes interspersed with said lobes such that said rotor is rotatable within said stator about said camshaft axis and defining alternating advance chambers and retard chambers, wherein said advance chambers receive oil in order to change the phase relationship between said crankshaft and said camshaft in an advance direction and said retard chambers receive oil in order to change the phase relationship between said camshaft and said crankshaft in a retard direction; said camshaft phaser further comprising a front cover closing off one end of said stator; and said sealing arrangement comprising an engine cover to camshaft phaser seal to seal between said engine cover and said front cover or between said actuator and said front cover.
 16. An internal combustion engine as in claim 15 wherein said engine cover includes a ring-shaped engine cover seal support extending axially from said engine cover toward said camshaft phaser and said engine cover to camshaft phaser seal is fixed to said engine cover seal support.
 17. An internal combustion engine as in claim 15 wherein said front cover includes a ring-shaped front cover sealing body extending axially from said front cover toward said engine cover such that said engine cover to camshaft phaser seal seals against said front cover sealing body.
 18. An internal combustion engine as in claim 15 wherein: said camshaft phaser further comprises a back cover closing off the other end of said stator, said back cover including a back cover central bore extending axially therethrough; said internal combustion engine further comprising a camshaft support which supports said camshaft; and said sealing arrangement further comprising an engine to camshaft phaser seal to seal between said camshaft phaser and said camshaft support.
 19. An internal combustion engine as in claim 18 wherein said camshaft support defines a camshaft support bore and said engine to camshaft phaser seal is located within said camshaft support bore.
 20. An internal combustion engine as in claim 19 wherein said back cover includes a ring-shaped back cover sealing body extending axially from said back cover into said camshaft support bore such that said engine to camshaft phaser seal seals against said back cover sealing body.
 21. An internal combustion engine as in claim 15 wherein said engine cover to camshaft phaser seal is fixed to said actuator.
 22. An internal combustion engine as in claim 21 wherein said actuator includes an actuator seal bore extending axially into said actuator and said engine cover to camshaft phaser seal is fixed within said actuator seal bore. 